This invention relates to processors that are resident on a printed circuit board and, in particular, to a system that provides a simplified manner of shutting down the operating system, executing on the processor, when a monitor, keyboard, and mouse are not provided.
It is a problem in the field of processors, resident on a printed circuit board, to properly terminate execution of any processes in an appropriate manner prior to powering down of the printed circuit board and the removal of the printed circuit board from its connector. This is particularly a problem when the printed circuit board includes a processor whose operating system must be shut down in a proper sequence to avoid the possibility of errors and there is no user interface with which to execute this sequence.
The Windows 95 and Windows NT operating systems, available from Microsoft Corporation, are frequently used in processors, such as personal computers, and require the user to follow a predetermined shut down sequence prior to powering off the personal computer. This sequence entails the user clicking on the xe2x80x9cSTARTxe2x80x9d icon on the display screen (such as a VGA monitor) of the personal computer, then selecting the xe2x80x9cSHUT DOWNxe2x80x9d option that is displayed by the resident operating system in response to this selection. The user can then select either xe2x80x9cSHUT DOWN THE COMPUTERxe2x80x9d or xe2x80x9cRESTART THE COMPUTERxe2x80x9d as options to initiate the operating system shut down. The personal computer then provides a display on the screen indicating that the operating system is in the shut down process and the user must wait to power off the computer. Once the Windows 95 or Windows NT operating system has executed the shut down process, the personal computer provides a display indicating to the user that it is now safe to power off the personal computer.
This above-described process is predicated on the computer system being equipped with a display and a user activated input device, such as a mouse or keyboard, to make the proper selections noted above. No other indication is generated to indicate that the operating system is shutting down or has successfully completed the shut down process. In the instance where such apparatus is not available, such as when the processor is resident on a printed circuit board which is mounted in a printed circuit card carrier, then the shut down process cannot be executed in the above-described manner. The user would have to connect a VGA monitor and input device to appropriate connectors provided on the printed circuit board in order to properly shut down the operating system. This is a costly and labor intensive process and is therefore undesirable. In addition, the printed circuit board typically does not have the space available on the front of the circuit pack to enable the placement of such connectors or the power sources to run a VGA monitor. Therefore, there presently is no system available that enables the simplified shutting down an operating system, resident on a printed circuit board, when a monitor and keyboard are not provided.
The above described problems are solved and a technical advance achieved by the present system for simplified operating system shutdown which enables the execution of the required operating system shutdown sequence without requiring the use of a monitor or a keyboard. This is accomplished by equipping the printed circuit board with a simple switch and an indicator device to provide the user interface to execute the operating system shutdown process. The user operates the switch, which activates the system for simplified operating system shutdown to initiate the required operating system shutdown process. The system for simplified operating system shutdown activates the indicator device in a first mode to notify the user that the shutdown process is now executing. The system for simplified operating system shutdown generates a message, which message is transmitted to the processor. This transmitted message comprises a system call for a shutdown and restart. This system call is an existing operating system call which represents the user clicking on the xe2x80x9cSTARTxe2x80x9d icon on the display screen of the personal computer, then selecting the xe2x80x9cSHUT DOWNxe2x80x9d option that is displayed by the resident operating system in response to this selection and then selecting the xe2x80x9cRESTART THE COMPUTERxe2x80x9d option that is displayed. The operating system responds to this system call by shutting down and then restarting its operation.
No indication is provided by the operating system to indicate the successful completion of the shut down process, but in the restart process, the operating system generates predetermined POST codes, which are detected by the system for simplified operating system shutdown. In response to the detected POST codes, the system for simplified operating system shutdown resets the processor and holds it in a reset state by setting the reset lead in a reset state. The system for simplified operating system shutdown then activates the indicator device to a second mode to indicate to the user that the operating system is shutdown and the circuit board can be removed from the circuit pack carrier.